She was treated more than 12 hours in the hospital before Pct. 1 Justice of the Peace B.H. Jameson pronounced her death at 5:12 a.m.

Her body was sent to the Tarrant County Medical Examiner's Office in Fort Worth for an autopsy, a routine procedure, Jameson said.

Cerliano said in the statement the sheriff's office was following up on the death.

"Texas Ranger Todd Martin along with Gregg County Sheriff's Investigators is conducting the investigation," the statement said. "The completed investigation will be forwarded to the Gregg County District Attorney's Office for review. The Texas Commission on Jail Standards was notified and reports will be filed with TCJS as well as the Office of the Attorney General."

An autopsy report for Duffie was pending Monday evening.

Duffie was the second inmate to die this year while in custody of the jail, and the fifth since 2010.

In March, Bobby Madewell Jr., 51, died from a combination of a syndrome known as excited delirium and other existing health problems, according to an autopsy report.

In June, Cheyenne Smith filed a lawsuit against the county for the 2011 death of her son, Micah Garner, who was found unresponsive in a holding cell despite having his vital signs checked every 30 minutes by county staff. The suit says Garner died because jail staff denied him proper medical treatment for withdrawal from heroin and methadone.

And in February a federal judge in Marshall approved a $1.9 million settlement agreement between Gregg County and survivors of Amy Lynn Cowling, who died in jail custody in Dec. 2010.

In that lawsuit the family argued the Cowling death could have been avoided if she had been allowed to take prescribed medicines for bipolar disorder and opiate withdrawal.

In July 2010, Misty Scott Beene died a natural death from lung cancer.

It was unknown late Monday what symptoms were plaguing Duffie, what disease she may have suffered or what medications she may have been on.